The early detection of corrosion on metallic structures and vehicles is an extremely time-consuming, costly and difficult task that implicates significant economic and safety considerations. For example, aircraft, spacecraft, automotive vehicles, watercraft, and various military vehicles operate and/or are exposed to corrosive environments.
For example, military and commercial aircraft undergo routine pre-flight, post-flight and periodic corrosion inspections and corrective maintenance. Often very expensive and time consuming techniques, such as x-ray radiography, ultrasonic imaging, and electromagnetic eddy current inspection methods may be used to detect corrosion. For many applications, damage due to corrosion is often difficult to detect. This is especially problematic on surfaces that are difficult to access with detection equipment.
In the past, various approaches have been employed and sensors developed to detect corrosion of metallic structures including the use of coatings applied to structure surfaces to sense corrosion. One approach that has been attempted to apply coatings intended to act as a sensor reactive to corrosion. For example, color-change pH indicators have been incorporated into organic coatings for determining the pH gradients associated with corrosion. In another example, fluorescent dyes have been applied to microelectronic test vehicles to detect pH changes associated with corrosion of aluminum or gold metallization under an applied electrical bias in a humid environment. Other attempts have included the use of fluorescing and color-change dyes that have been applied to aluminum after corrosion has begun in order to identify the location of the hydrous aluminum oxide corrosion product. More recently, paint has been formulated to include different chemicals that fluoresce upon oxidation or upon complex-action with metal cations formed by the corrosion process.
Many prior fluorescent and luminescent paints have required that a large portion of the coating be a visual indicator. Such a large concentration of the additive may negatively affect the performance of the coating. Moreover, many types of pigments alter the coating color and appearance. Such indicators are typically organic based compositions that may deteriorate and lose their usefulness over time. The organic indicators may also migrate between coats, so it may not be apparent after time has passed whether a second layer was satisfactorily applied. In addition, many indicators do not show fluorescence in a color that is easy for the human eye to detect, so that the contrast between the coating and the uncoated areas are not readily detected.
However, no method, system or coating has been developed that provides an inexpensive and more comprehensive technique for visually revealing locations of corrosion, even in difficult to inspect locations.
Therefore, a system, method and coating is needed for improved corrosion detection. Such a system, method and coating should provide for simple, effective application, reliable overall coating, and simple corrosion detection.
The foregoing examples and limitations associated therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon reading of the specifications and study of the drawings.